Cooling towers

ABSTRACT

A method for the treatment of water used in a cooling tower, the method including the steps of withdrawing a portion of the water from a basin of the cooling tower, subjecting the water to a magnetic treatment, and withdrawing blow down water for use in irrigation.

FIELD OF THE INVENTION

The present invention relates to water treatment and more particularly, relates to a water treatment system and a method for utilizing blow down water for irrigation.

BACKGROUND OF THE INVENTION

Cooling towers are basically heat removal devices used to transfer processed waste to heat the atmosphere. Cooling towers may either use the evaporation of water to remove processed heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating water used in oil refineries, chemical plants, power stations, building cooling, etc. The towers vary in size from small roof-top units to very large structures that can be as much as 200 meters tall and 100 meters in diameter.

Cooling towers can be classified into different types—HVAC (air conditioning) or industrial duty. An HVAC cooling tower is used in conjunction with a chiller. Water-cooled chillers are normally more energy efficient than air cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures. Air cooled chillers must reject heat at the dry-bulb temperature and thus have a lower average reverse—Carnot cycle effectiveness. Large office buildings, hospitals and schools typically use one or more cooling towers as part of their air conditioning system. HVAC's use of a cooling tower pairs a cooling tower with a water-cooled chiller or water-cooled condenser.

Industrial cooling towers are generally used to remove heat from various sources such as machinery or heated process material. A primary use of large industrial cooling towers is to remove the heat absorbed in circulating cooling water systems such that are used in many different types of plants including power plants, petroleum refineries, etc. A cooling tower serves to dissipate heat into the atmosphere instead of using circulating water which is discharged. Discharging large amounts of hot water can raise the temperature of a receiving river or lake to a non acceptable level for the local ecosystem.

SUMMARY OF THE INVENTION

One of the problems associated with cooling towers is the build up of scale. If not properly treated, the scale will impede the flow of water and eventually completely seal the pipes. In order to prevent the above, there are two methods which can be utilized. The first method is the use of chemicals. The problem with such chemical use is the relatively high cost associated therewith as well as disposal of the blow down liquid. This is the portion of the circulating water flow that is removed in order to maintain the amount of dissolved solids and other impurities at an acceptable level. Typically, about 0.4% goes to the sewer. For a 500 ton chiller, this can be equal to approximately 9,000 gallons per day.

A further or potential problem with cooling towers is legionnaire's disease. Common sources of legionella include cooling towers, domestic hot water systems, fountains and similar disseminators. It has been found that legionella can spread through the air up to 6 km from a large contained cooling tower.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a system for the treatment of water in a cooling tower.

It is a further object of the present invention to provide a method for the treatment of water in a cooling tower including a method for the disposal of the blow down liquid.

According to one aspect of the present invention there is provided a method for the treatment of water used in a cooling tower, the method comprising the steps of drawing a portion of the water from a basin of the cooling tower, passing the portion of the water through a magnetic treatment device wherein the water and flux lines from the magnetic treatment device intersect at an angle and withdrawing blow down water and using said blow down water for irrigation.

The magnetic treatment means are utilized to generate magnetic lines of flux through which the water passes. The preferred arrangement is that shown in U.S. Pat. No. 5,149,438 (the teachings of which are hereby incorporated by reference) wherein water is directed in a spiral manner such that it is subject to magnetic lines of flux at an angle. The device can be used to control and even remove scale previously formed.

As is known in the art, periodically the cooling towers must be blown down with a portion of the liquid known as the blow down liquid being dumped to the sewer system.

In the present invention, the water from the blow down is utilized for irrigation and avoids dumping to the sewer system. The blow down water usually has a relatively high concentration of calcium which has been found beneficial in the growing of healthy plants and fruit bearing plants. Calcium plays a role in the fertility of the soil by reducing its acidity. The blow down water used for irrigation is preferably used in close proximity to the cooling towers. In many operations, greenery is growing nearby and can range from roof top greenery to greenery or shrubbery on the ground. Naturally, the irrigation water could also be stored in a container and pumped or transported to other sites for irrigation.

When the water in the cooling tower is subjected to a magnetic catalytic treatment as in the present invention, the blown off liquid is typically less than 100%. The blow off liquid is concentrated with minerals such as calcium, magnesium and iron which are suitable for use as nutrients for grass and plants. A 400 ton cooling tower normally circulates at approximately 1200 GPM with the bleed off or blow down being 4.8 GPM which is equal to approximately 6,900 gallons of water per day.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the invention, reference will be made to the accompanying drawings illustrating an embodiment thereof, in which:

FIG. 1 is a perspective view of a structure and associated cooling tower; and

FIG. 2 is a schematic view illustrating operation of the system.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings in greater detail and by reference characters thereto, there is illustrated a building 10 which has a cooling tower 12 associated therewith. It will be understood that cooling tower 12 may be utilized in conjunction with other than building 10 including, for example, industrial cooling towers such as utilized with power plants, petroleum refineries, etc.

Cooling tower 12 and the associated system are illustrated in greater detail in FIG. 2 and reference will now be had thereto. Cooling tower 12 has a central portion 80 and a basin 82 associated therewith. This is a conventional structure in the art. A recirculating loop 84 has a condenser 86 associated therewith.

The magnetic treatment system of the present invention is generally designated by reference numeral 14 and includes an inlet conduit 16 extending from basin 82 for removing a portion of the liquid therefrom. Inlet conduit 16 feeds the liquid to a pump 18 wherein the liquid is pumped through a conduit 19. A purge valve 20 is mounted on conduit 19. A further valve 21 is mounted between purge valve 20 and a centrifuge 22. Centrifuge 22 includes a purge valve 24 located at the bottom thereof and which can be used to discharge material to sewer 25. The liquid is fed from centrifuge 22 through conduit 26 on which there is mounted a conductivity probe 28. Conduit 26 feeds the fluid to catalysers 30, 32 each having a valve 34, 36 respectively at the outlet thereof. Subsequently, the liquid goes to an outlet 38 where it is fed back into basin 82.

A bypass conduit 39 has a valve 40 mounted thereon intermediate a first manometer 42 and a second manometer 44.

The system preferably includes a biocide-algicide injector 46 and pumps 47 for bacterial and algicide growth control.

The system will include suitable controls including a conductivity control 48, a purge control 50 and a pump control 52.

A make-up line 56 is provided to feed additional water as required. Mounted on make-up line 56 is a further catalyser 58.

There is also provided a further catalyser 62 which is mounted in association with recirculating loop 84 to withdraw a small amount of water therefrom and subject the same to the catalytic treatment.

Purge valve 20 has a conduit 66 associated therewith for feeding the liquid to a tank or storage device 68. From there, the liquid may be used for irrigating greenery 70.

The greenery 70 may be located at any desired location including, for example, on the roof of building 10. Alternatively, the irrigation water may be transported to other locations for use.

Each of the catalysers 30, 32, 58 and 62 subject the water to a magnetic treatment which is preferably of the type taught in U.S. Pat. No. 5,149,438, the teachings of which are hereby incorporated by reference.

The catalysers 30, 32,58, 62 are designed to treat approximately 10% of the flow of the water from the basin to the cooling tower. Naturally, this may be varied, but this amount has been found to provide for an effective treatment.

It will be understood that the above described embodiment is for purposes of illustration only and that changes and modifications may be made thereto without departing from the spirit and scope of the invention. 

I claim:
 1. A method for the treatment of water used in a cooling tower, the method comprising the steps of: drawing a portion of said water from a basin of said cooling tower; passing said portion of said water through a magnetic treatment device wherein said water and flux lines from said magnetic treatment device intersect at an angle; and withdrawing blow down water and using said blow down water for irrigation.
 2. The method of claim 1 further including subjecting make up water for said cooling tower to a magnetic treatment.
 3. The method of claim 2 further including the step of subjecting water flowing from said basin to said cooling tower to a magnetic treatment. 